Lustrous pile fabric based on polypropylene



United States Patent 3,505,097 LUSTROUS PILE FABRIC BASED ON POLYPROPYLENE Charles B. Ratclitfe, Charlotte, N.C., assignor to Hercules Incorporated, Wilmington, Del., a corporation of Delaware No Drawing. Filed Apr. 20, 1967, Ser. No. 632,196 Int. Cl. B4411 1/14 US. Cl. 117-64 4 Claims ABSTRACT OF THE DISCLOSURE Lustrous polypropylene pile fabrics, simulating natural fur, are prepared by treating the fabric with an aqueous emulsion of a silicone oil and a mineral oil and polishing. The treating emulsion can be applied to the fabric after appropriate treatments to remove process sizing or it can be applied during spinning in lieu of other types of process sizing.

This invention relates to the preparation of lustrous pile fabrics from polypropylene.

It is known to prepare pile fabrics in the nature of coat liners, boot liners, imitation fur and the like from synthetic organic staple fibers, particularly the acrylic fibers because of their excellent heat insulating properties. Such fabrics are prepared, according to one known technique, by a process which comprises mechanically brushing a sliver knitted fabric under conditions which remove a major portion of the crimp from the tips of the individual staple fibers, leaving them substantially straight at the tips, but still crimped throughout most of their length, and imparting a luster thereto. The luster is a critical characteristic of the fabric, since it is desired to approximate, as nearly as possible, the appearance of natural fur.

It would be highly desirable to apply stereoregular polypropylene to this use, since it not only possesses heatinsulating powers comparable to those of the acrylic fibers mentioned above, but, in addition, is substantially cheaper and more soil resistant, thus easier to clean. Unfortunately, when the mechanical brushing technique described above is applied to fabrics based upon polypropylene, good results are not obtained. It is found that at the temperatures required to remove the crimp and impart luster to the fabric, a substantial amount of fusion of the polypropylene fibers takes place.

In accordance with this invention, a novel method has now been found whereby a 'high luster can be produced on pile fabrics based upon polypropylene sliver knitted fabrics. Generally, this method contemplates treatment of the fabric with an oil emulsion followed by low temperature brushing or polishing. More specifically, the invention comprises treating a polypropylene pile fabric with an emulsified mineral oil and thereafter brushing at relatively low temperature. In some cases, the emulsions can contain, additionally, a silicone lubricant.

The composition with which the fabric is treated is an emulsion, preferably, but not necessarily in water, of a silicone oil and a mineral oil, with suitable emulsifying aids. The treating composition can contain about 0 to 8% preferably 0.5 to 6% by weght of the silicone oil, and about 0.5 to 4% preferably 0.5 to 3% by weight of the mineral oil. The total amount of emulsifying agent to be employed will depend upon the specific agent being used and the specific oils being used. In general, however, this will usually be between about .01 and 1%.

The silicone oils which can be used are a well-known class of materials, more correctly known as organopolysiloxanes. These are polymers characterized by a linear molecular skeleton made up of silicon-oxygen linkages with low molecular weight organic groups attached to the 3,505,097 Patented Apr. 7, 1970 silicone atoms. The dimethylpolysiloxanes are a preferred class of silicone oils.

Any of the well-known mineral oils including both petroleum and shale oils can be used in the treating compositions. Typical of those are petrolatums and heavy hydrocarbons.

In preparing the emulsions contemplated for use in this invention, the ingredients are simply agitated vigorously in water containing the desired emulsifying agent. In some cases, it is desirable to include a small amount of a medium boiling, volatile hydrocarbon such as benzene, xylene, or the like, to dissolve the other ingredients, thereby reducing their viscosity and facilitating emulsification.

For best results, the emulsion is preferably applied to a polypropylene fabric from which all or substantially all of the normal spin finish has been removed. It has been found that the presence of the spin finish materials almost always has an effect on the eflicacy of the oil emulsion to effect the desired crimp removal and reproducible luster formation. The spin finish can be removed by known means. A good way to accomplish this is by extracting with perchlorethylene or by boiling in soda ash or in certain condensation products of oxy compounds. The sizing removal method is not critical so long as substantially all of the same is removed and no additional con taminant is placed on the fabric.

In treating the polypropylene fabrics according to this invention the temperature at which treatment is effected is important. As stated, one of the problems encountered with prior art techniques was that the temperature required to effect removal of the crimp was so high as to cause fusion of the fibers. With the process of this invention, it is possible to operate at temperatures sufliciently lower than those previously used to avoid such fusion. Generally, temperatures from about 280 F. to about 305 F. have been found satisfactory although temperatures somewhat above or below this range can be used in certain cases. However, temperatures above about 310 F. should not be used for the reasons aforesaid and temperatures below about 260 F. will generally not be used because of inferior results.

The treating or polishing emulsion can be applied to the fabric in any convenient way, as by dipping, spraying, brushing and the like. It is preferred to apply it by spraying since this method has been found to be most easily controlled at the relatively low treatment levels desired. It is also convenient to apply the emulsion during the spinning of fiber in lieu of other spin finishes, thus eliminatng the need for removal of spin finish before polishing the fabric. In general, the treatment level should be such as to deposit on the fabric a combined total of about 0.5 to 4% silicone oil, mineral oil, and emulsifier, based on the weight of the fabric.

The following examples illustrate but do not limit the invention. Parts and percentages are by weight unless otherwise specified. Good crimp retention indicates that crimp has been removed only from the tips of the fibers.

EXAMPLE 1 An emulsion was prepared by suspending 1 part min eral oil and 0.5 part dimethylpolysiloxane oil in parts water at F. containing 0.25 part modified alkyl sulphate emulsifying agent. This mixture was agitated vigorously for about 15 minutes to obtain a stable emulsion.

This emulsion was applied by spraying to a knit polypropylene boot pile fabric having 20 to 26 oz. of 6 denier, 1%" staple yarn/60" running yard and sheared to pile height. This yarn had been scoured with a condensation product of an oxy compound (CIBA Product A1008). The emulsion was applied to a level of 1% by weight add-on to the fabric. The fabric was immediately passed under the polishing rolls of a standard pile fabric polishing machine (Egan polisher) with roll surface temperature at 280 E, medium pressure, at about yards/ minute. Two passes were made through the unit in alternate directions in order to polish two sides of the fiber. The resultant fabric had luster and crimp retention comparable to that obtained with acrylic fibers.

EXAMPLE 2 Following the general procedure of Example 1, an emulsion was prepared containing about 2 parts mineral oil, 0.5 part dimethylpolysiloxane, 025 part of an anionic emulsifier and 1.5 parts xylene, and 95.75 parts water. The emulsion was sprayed onto the fabric to a level of about 4% add-on, and the fabric was dried at about 250 F before polishing.

The treated fabric was passed through the polishing machines, two passes in each direction at 6 yards/minute, under medium pressure at 270 F. roll temperature. The fabric exhibited very good luster and crimp retention.

EXAMPLE 3 The emulsion in this example consisted of 3 parts min eral oil, 3 parts benzene, 0.5 part silicone oil, 0.125 part anionic emulsifier and water to make 100 parts.

This was applied to fabric to 2% add-on level and passed through the polishing machine under medium pres sure at 3 yards per minute with the roll temperature at 300 F. Excellent luster and crimp retention resulted.

EXAMPLE 4 An emulsion, prepared as in Example 1, containing 3% benzene, 3% mineral oil, and 0.25% emulsifier, was applied to the fabric at 2% add-on level. This fabric was treated in the polishing unit at 6 yards/minute, under moderate pressure, two passes in each direction with roll temperature at 270 F. Good luster was obtained on the fabric, with crimp removed only at the tips of the fibers.

EXAMPLE 5 The emulsion used in this example consisted of about 3% mineral oil, 5% anionic fabric softener, and 0.25% anionic emulsifier in water. This emulsion was applied to the fabric to a 2% by weight add-on level and dried for minutes at 250 F. prior to polishing. Polishing was effected at 3 yards/ minute, medium pressure at a roll temperature of 290 F., four passes in each direction. Excellent luster and crimp retention resulted.

EXAMPLE 6 Example 5 was repeated except that the treatment on the polishing rolls was carried out in three passes in each direction, 1 pass at 290 E, 1 pass at 270 F., and the third pass at 260 F. The first pass was effected in the knit direction. The resulting fabric had excellent luster, closely resembling natural fur.

EXAMPLE 7 In this example, the emulsion consisted of 2% mineral oil, 6% anionic fabric softener, and 0.25% anionic emulsifier in water.

The fabric to which the above emulsion was applied was prepared from polypropylene yarn which had been heat treated at 285 F. in an autoclave to stabilize the crimp prior to carding and knitting. The knitted fabric was scoured with oxy compound and tip sheared to remove mated tips. Emulsion was added to a 2% add-on level and dried at 250 F. for 20 minutes before polishing. Polishing was effected at 290 F. at 5 yards per min: ute under medium pressure, one pass each direction. Crimp retention and luster were good. A similar result was obtained when the yarn was scoured before heat treatmg.

EXAMPLE 8 Example 5 was repeated except that the emulsion was applied to the fibers during the initial spinning, prior to drawing. The yarn was thereafter treated in the usual way, made into a fabric, and polished as in Example 5. Results were substantially the same as those realized in Example 5.

What I claim and desire to protect by Letters Patent is:

1. A process for producing lustrous sliver knitted fab ric based on polypropylene fibers which comprises ap* plying to said fibers an emulsion of about 0.5 to 4% mineral oil and about 0 to 8% silicone oil in water and polishing a fabric containing said fibers at a temperature between about 270 F. and 305 F.

2. A process for producing lustrous sliver knitted fabric according to claim 1 wherein the emulsion comprises about 0.5 to 3% mineral oil and about 0.5 to 6% silicone oil in water.

3. The process of claim 1 where the emulsion is applied to the fibers as a spin finish during the manufacture of said fibers.

4. The process of claim 1 where the emulsion is applied to the fibers after the same have been made into a fabric.

References Cited UNITED STATES PATENTS 2,690,426 9/1954 Jefferson 117l 39.5

2,727,860 12/1955 Duke et a] 117-139.5

2,731,364 1/1956 Reibnitz 117-64 3,009,830 11/1961 Levine 1l7139.5 3,193,409 7/1965 Keller et a1. 117139.5

3,286,322 11/1966 Sneary ll7138.8

3,288,622 11/1966 Weiss 117-1395 WILLIAM D. MARTIN, Primary Examiner WILLIAM R. TRENOR, Assistant Examiner US. Cl. X.R. 

